Book excerpt: Feedback is arguably the most critical and powerful aspect of teaching and learning. Yet, there remains a paradox: why is feedback so powerful and why is it so variable? It is this paradox which Visible Learning: Feedback aims to unravel and resolve. Combining research excellence, theory and vast teaching expertise, this book covers the principles and practicalities of feedback, including: the variability of feedback, the importance of surface, deep and transfer contexts, student to teacher feedback, peer to peer feedback, the power of within lesson feedback and manageable post-lesson feedback. With numerous case-studies, examples and engaging anecdotes woven throughout, the authors also shed light on what creates an effective feedback culture and provide the teaching and learning structures which give the best possible framework for feedback. Visible Learning: Feedback brings together two internationally known educators and merges Hattie’s world-famous research expertise with Clarke’s vast experience of classroom practice and application, making this book an essential resource for teachers in any setting, phase or country.